1. Field of the Invention
The invention generally relates to a computer transmission interface, and more specifically to a transmitting circuit, a receiving circuit, a transceiver circuit, an interface switching module and an interface switching method for Serial Advanced Technology Attachment (SATA) and Serial Attached Small Computer System Interface (SAS).
2. Description of the Related Art
FIG. 1 is a circuit diagram of a transmitting circuit in accordance with the SATA and the SAS standards. FIG. 2 is a circuit diagram of a receiving circuit in accordance with the SATA and the SAS standards.
Referring to FIG. 1 and FIG. 2, a transmitting circuit 100, including a switch 110 and two variable resistors 101, receives a transmitting data signal TXD to generate a first transmitting signal TXP and a second transmitting signal TXN. A receiving circuit 200, including a differential amplifier 210 and two variable resistors 101, receives a first receiving signal RXP and a second receiving signal RXN to generate a receiving data signal RXD. High-speed serial transmission interface specifications, such as SATA and SAS, define 50-ohm differential impedance elements 101 embedded in the transmitting circuit or the receiving circuit for impedance matching. Thus, when high-speed serial signals are transmitted via physical layer, even too much cyclic redundancy check (CRC) errors do not cause communication link failure. However, precision resistors are used as differential impedance elements in prior art but are not operable in impedance modulation.
Traditionally, a host or a device having same or different transmission interfaces uses a plurality of bridges for data transmission. A minimum of three transceivers is required for a bridge with a switching mechanism among a plurality of high-speed serial signals under the current SATA and SAS architecture, which is complex and high-cost in hardware design. If a plurality of transmission interfaces can be integrated in a single unit, it will significantly meet the convenience in use and reduce use cost.